I am developing a BHO for IE in C# that controls the navigation flow of IE by checking the URL in onBeforeNavigateEvent.
Everything works fine except that when a link is opened in a new tab then some of the tabs opened as About:Blank.
I have checked the logs and also debugged the BHO no exception is thrown. However in the case of About:Blank BHO is initiated SetSite and GetSite methods are called but navigation event is not fired.
Also it happens when links are opened in new tab rapidly.
For testing purpose I disabled the addon and IE worked fine i.e. no About:Blank page.
Loading time of BHO is 0.1s and Navigation time is 0.5s
So, what could be the issue ?
The source I followed to build this BHO is here
Current Environment: IE 11, Windows 10
Interop.cs
using System;
using System.Runtime.InteropServices;
namespace IE_BHO
{
[
ComImport(),
ComVisible(true),
InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
Guid("FC4801A3-2BA9-11CF-A229-00AA003D7352")
]
interface IObjectWithSite
{
[PreserveSig]
int SetSite([In, MarshalAs(UnmanagedType.IUnknown)] object site);
[PreserveSig]
int GetSite(ref Guid guid, out IntPtr ppvSite);
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OLECMDTEXT
{
public uint cmdtextf;
public uint cwActual;
public uint cwBuf;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
public char rgwz;
}
[StructLayout(LayoutKind.Sequential)]
public struct OLECMD
{
public uint cmdID;
public uint cmdf;
}
[ComImport(), ComVisible(true),
Guid("B722BCCB-4E68-101B-A2BC-00AA00404770"),
InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
public interface IOleCommandTarget
{
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int QueryStatus(
[In] IntPtr pguidCmdGroup,
[In, MarshalAs(UnmanagedType.U4)] uint cCmds,
[In, Out, MarshalAs(UnmanagedType.Struct)] ref OLECMD prgCmds,
//This parameter must be IntPtr, as it can be null
[In, Out] IntPtr pCmdText);
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int Exec(
//[In] ref Guid pguidCmdGroup,
//have to be IntPtr, since null values are unacceptable
//and null is used as default group!
[In] IntPtr pguidCmdGroup,
[In, MarshalAs(UnmanagedType.U4)] uint nCmdID,
[In, MarshalAs(UnmanagedType.U4)] uint nCmdexecopt,
[In] IntPtr pvaIn,
[In, Out] IntPtr pvaOut);
}
[Guid("6D5140C1-7436-11CE-8034-00AA006009FA")]
[InterfaceType(1)]
public interface IServiceProvider
{
int QueryService(ref Guid guidService, ref Guid riid, out IntPtr ppvObject);
}
[
ComVisible(true),
Guid("4C1D2E51-018B-4A7C-8A07-618452573E42"),
InterfaceType(ComInterfaceType.InterfaceIsDual)
]
public interface IExtension
{
[DispId(1)]
string ActivateEndPoint(string licenseKey, string userAgent);
}
}
BHO.cs
using Microsoft.Win32;
using SHDocVw;
using System;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.Expando;
using System.Security.Permissions;
using System.Threading.Tasks;
using mshtml;
using System.Reflection;
using System.Diagnostics;
namespace IE_BHO
{
[
SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode),
ComVisible(true),
Guid("BDCB9FDA-8370-40D9-96C9-9D4B4C25C0D8"),
ClassInterface(ClassInterfaceType.None),
ProgId("myExtension"),
ComDefaultInterface(typeof(IExtension))
]
public class BHO : IObjectWithSite, IOleCommandTarget, IExtension
{
object _site;
IWebBrowser2 _webBrowser2;
#region Implementation of IObjectWithSite
int IObjectWithSite.SetSite(object site)
{
_site = site;
if (site != null)
{
var serviceProv = (IServiceProvider)_site;
var guidIWebBrowserApp = Marshal.GenerateGuidForType(typeof(IWebBrowserApp));
var guidIWebBrowser2 = Marshal.GenerateGuidForType(typeof(IWebBrowser2));
IntPtr intPtr;
serviceProv.QueryService(ref guidIWebBrowserApp, ref guidIWebBrowser2, out intPtr);
_webBrowser2 = (IWebBrowser2)Marshal.GetObjectForIUnknown(intPtr);
((DWebBrowserEvents2_Event)_webBrowser2).BeforeNavigate2 += OnBeforeNavigate2;
((DWebBrowserEvents2_Event)_webBrowser2).BeforeScriptExecute += S2_BeforeScriptExecute;
((DWebBrowserEvents2_Event)_webBrowser2).DownloadComplete += BHO_DownloadComplete;
}
else
{
((DWebBrowserEvents2_Event)_webBrowser2).BeforeNavigate2 -= OnBeforeNavigate2;
((DWebBrowserEvents2_Event)_webBrowser2).BeforeScriptExecute -= S2_BeforeScriptExecute;
((DWebBrowserEvents2_Event)_webBrowser2).DownloadComplete -= BHO_DownloadComplete;
_webBrowser2 = null;
}
return 0;
}
int IObjectWithSite.GetSite(ref Guid guid, out IntPtr ppvSite)
{
IntPtr punk = Marshal.GetIUnknownForObject(_webBrowser2);
int hr = Marshal.QueryInterface(punk, ref guid, out ppvSite);
Marshal.Release(punk);
return hr;
}
public void OnBeforeNavigate2(object pDisp, ref object URL, ref object Flags, ref object TargetFrameName, ref object PostData, ref object Headers, ref bool Cancel)
{
try
{
UrlObj dto = UrlManager.CheckUrl(URL.ToString());
if (dto.IsInList)
{
Cancel = true;
_webBrowser2.Navigate2("www.google.com");
}
}
catch (Exception ex)
{
}
}
private void S2_BeforeScriptExecute(object pDispWindow)
{
ExposeMethodstoJS();
}
private void BHO_DownloadComplete()
{
ExposeMethodstoJS();
}
private void ExposeMethodstoJS(string calledBy)
{
try
{
HTMLDocument doc = _webBrowser.Document as HTMLDocument;
if (doc != null)
{
IHTMLWindow2 tmpWindow = doc.parentWindow;
dynamic window = tmpWindow;
IExpando windowEx = (IExpando)window;
PropertyInfo p = windowEx.AddProperty("myExtension");
p.SetValue(windowEx, this);
}
}
catch (Exception ex)
{
}
}
#endregion
#region Implementation of IOleCommandTarget
int IOleCommandTarget.QueryStatus(IntPtr pguidCmdGroup, uint cCmds, ref OLECMD prgCmds, IntPtr pCmdText)
{
return 0;
}
int IOleCommandTarget.Exec(IntPtr pguidCmdGroup, uint nCmdID, uint nCmdexecopt, IntPtr pvaIn, IntPtr pvaOut)
{
return 0;
}
#endregion
#region Implementation of IExtension
string IExtension.GetDetails()
{
return "Methods Exposed";
}
#endregion
#region COMRegistration
[ComRegisterFunction]
public static void RegisterBHO(Type type)
{
RegistryKey registryKey = Registry.LocalMachine.CreateSubKey(@"Software\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects");
RegistryKey guidKey = registryKey.CreateSubKey(type.GUID.ToString("B"));
registryKey.Close();
guidKey.Close();
}
[ComUnregisterFunction]
public static void UnregisterBHO(Type type)
{
RegistryKey registryKey = Registry.LocalMachine.OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects", true);
string guid = type.GUID.ToString("B");
if (registryKey != null)
{
registryKey.DeleteSubKey(guid, false);
}
}
#endregion COMRegistration
}
}
